MEIOSIS

Question 1

MEIOSIS

Answer 1

cell division that produces reproductive cells in sexually reproducing organisms in the gonads

Question 2

MEIOSIS IN ANIMALS

Answer 2

testes of male animals

ovaries of female animals

Question 3

MEIOSIS IN PLANTS

Answer 3

regions called sporangia that produce spores in the anther

ovaries in the pistil

Question 4

INTERPHASE

Answer 4

• DNA replication takes place and single stranded chromosomes become 2ble
• each chromosome = two chromatids & one centromere

Question 5

PURPOSE OF MEIOSIS

Answer 5

• forming gametes (diploid becomes haploid gametes which fuze to form zygotes)
• forming spores (haploid spores grow into gametophytes which produce gametes that fuze to form diploid zygotes)

Question 6

IMPORTANCE OF MEIOSIS

Answer 6

• maintains chromosome number w sexual reproduction
• essential for gamete production
• leads to genetic variation in populations
• repairing, growth, and replacing

Question 7

HOMOLOGOUS PAIR

Answer 7

one chromosome from mother and one from father, ensures organisms have characteristics from both parents

Question 8

KARYOTYPE

Answer 8

complete diploid set of chromosomes arranged according to shape and size within an organism’s body cells

Question 9

HUMAN KARYOTYPE

Answer 9

22 ordinary chromosome pairs

one pair of gonosomes

Question 10

GONOSOMES

Answer 10

sex chromosomes

Question 11

HUMAN DIPLOID CHROMOSOME NO.

Answer 11

46

Question 12

MALE VS FEMALE GONOSOMES

Answer 12

M - XY

F - XX

Question 13

CELL CYCLE

Answer 13

the time period during which the cell grows, divides and replicates genetic material

Question 14

MITOSIS

Answer 14

the division of somatic cells for growth, repairing damaged tissues and ace rep

Question 15

PROPHASE

Answer 15

• chromatin network threads shorten and thicken to be visible as double stranded chromosomes
• nuclear membrane and nucleolus disappear
• centrosome duplicates and centrioles move to opposite poles
• spindle fibers form between the centrioles

Question 16

METAPHASE

Answer 16

chromosomes move to the equator in a single row and some spindle fibers attach to centromeres

Question 17

ANAPHASE

Answer 17

• each centromere divides in two
• chromatids separate and move to opposite poles
• now known as daughter chromosomes
• cytokinesis begins

Question 18

CYTOKINESIS

Answer 18

division of the cytoplasm

Question 19

TELOPHASE

Answer 19

• daughter chromosomes position @ the poles
• nuclear membrane is formed around each group of d.c.
• nucleolus forms in each nucleus
• cytokinesis occurs
• two identical daughter cells are formed

Question 20

MEIOSIS I

Answer 20

chromosome number is halved and genetic material is exchanged

Question 21

MEIOSIS II

Answer 21

like normal mitosis where daughter chromosomes separate

Question 22

PROPHASE I

Answer 22

• chromatin network shortens and thickens = chromosomes
• homologous chromosomes arrange in pairs
• two chromosomes of each pair lie close tog to form a bivalent. each chromosome splits and are known as sister chromatids
• crossing over occurs and segments of chromatids break off and are exchanged
• nucleolus/membrane disappear and centrosomes duplicates and moves to opp poles of the cells
• spindle fibers develop between centrioles

Question 23

CROSSING OVER

Answer 23

results in the recombination of genetic material between maternal and paternal chromosomes

Question 24

CHIASMATA

Answer 24

the points at which the chromatids cross over and breakages occur

Question 25

METAPHASE I

Answer 25

bivalents position on the equator, w chromosomes in a double row on either side. spindle fibers attach to centromeres

Question 26

ANAPHASE I

Answer 26

- spindle fibers contract, pulling chromosomes towards poles - homologous chromosomes separated - each chro of the bivalent moves to opp poles and cytokinesis begins

Question 27

TELOPHASE I

Answer 27

- chromosomes group at the poles - spindle fibers disappear - nuclear membrane forms around each group and cytokinesis is complete

Question 28

PROPHASE II

Answer 28

- each chromosomes has two chromatids and a centromere - nucleolus/membrane disappear - a spindle forms (centrioles at opp poles and fibres)

Question 29

METAPHASE II

Answer 29

chromosomes align in single row on the equator, spindle fibers attach

Question 30

ANAPHASE II

Answer 30

- centromere of each chromosomes splits in two, and move to sep poles - chromatids are now known as daughter chromosomes and cytokinesis begins

Question 31

TELOPHASE II

Answer 31

- d.c group at poles and spindle fibers disappear - nuclear mem/olus forms - cytokinesis occurs - invagination in animals, cell plate develops in plants on equator - cytokinesis complete, 4 daughter cells formed

Question 32

GENETIC VARIATION

Answer 32

the differences that occur as a result of diff gene combinations between the organisms of a species

Question 33

ABNORMAL MEIOSIS

Answer 33

when meiosis doesn't proceed normally, changes in chro no. or structure occurs

Question 34

ANEUPLOIDY

Answer 34

a condition where there are extra/missing chromosomes

Question 35

DOWN SYNDROME

Answer 35

- 47 chromosomes - at chromosome pair no. 21 - aka Trisomy 21

Question 36

DS CHARACTERISTICS

Answer 36

- small eyes - flat forehead and nose bridge - mental retardation - large tongue

Question 37

SIMILARITIES BETWEEN MEI AND MIT

Answer 37

- both are cell division - both require DNA replication in interphase - both have PMAT

Question 38

DIFF BETWEEN MEI AND MIT

Answer 38

- only 1 division in mit, two in mei - no homo pairing in mit - no crossing over in mit - 2 d.c. formed in mit, 4 in mei

Question 39

TWO TYPES OF CELL DIVISION

Answer 39

meiosis and mitosis